滇西北金沙江带早石炭世深海沉积的发现

DISCOVERY OF EARLY CARBONIFEROUS DEEP-SEA SEDIMENTS FROM JINSHA BELT, NW YUNNAN

70年代末以来,金沙江蛇绿岩带或金沙江缝合带受到人们的重视,其地质证据主要在滇西北德钦—川西南得荣一带(张之盂和金蒙,1979;陈炳蔚,1983;黄汲清等,1984;陈炳蔚等,1991)。由于该地区构造复杂,地形险峻,交通不便,研究程度不高。

The Early Carboniferous radiolarians and conodonts were found from the radio-larian chert and siliceous limestone interbeds within pillow basalts along a small branch of Jinsha River in Xiaruo district, Deqin County, northwest Yunnan.The radiolarian assemblage includes Albaillella indensis Won, Asteroentactinia biaciculata Nazalov, Belowea aff. valiabilis (Ormiston and Lane), Callela parvisp-inosa Won, Entactinia variospina (Won), Eostylodictya eccenlrica Ormiston and Lane, Tetragregnon sycamorensis Ormiston and Lane, and Trilonche cimelia Ormiston and Lane, etc., that can be correlated with the late Tounaician early Visean radiolarian assemblage of western Germany (Won, 1983) and the Osagean radiolarian assemblage of Oklahoma, North America. The conodont assemblage is characterized by Gnathodus typicus Cooper, G. girtyi rhodesi Higgins, and Spathognathodus sp., etc., indicative of later Early Carboniferous. This discovery indicates that the opening time of the Jinsha Suture was not later than Early Carboniferous.